We should know very soon whose iPhone will be on the waiting list for the Apple Intelligence limited preview option as the iOS 18 beta will enter testing in the summer.
While Apple has built its own AI servers and operating system to service the Apple Intelligence technologies permeating iOS 18, it would want to gauge the load better before the public release so as not to give users a bad experience with functions not working or moving slow due to high demand.
The slow response reference might also mean that Apple Intelligence is only geared to certain markets and could be rolled out more gradually or not with the full list of features everywhere.
In short, Apple’s AI revolution will come with its characteristic slow and steady style, for now covering features that are already available elsewhere, just integrated as seamlessly as possible into iOS 18.